Pension plans 5 (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation (as a percent)	35.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation (as a percent)	65.00%
U.S. Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	7.50%	7.50%	8.00%
2016	$ 53.6
2017	37.1
2018	38.4
2019	41.4
2020	41.7
Years 2021 - 2025	$ 220.5
Weighted-average discount rate	4.25%	4.00%
Non-U.S. Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	6.00%	5.78%	6.01%
2016	$ 5.4
2017	1.5
2018	1.4
2019	1.7
2020	1.5
Years 2021 - 2025	$ 11.7
Weighted-average discount rate	3.96%	3.67%
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Settlement loss (gain)	$ (0.1)	$ (1.8)	$ (0.4)